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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb6c5cd03f2a1118d0a5050e9d54b6adfff16210bbcbbc65138b845e9ee0bc6c' 
  AND token = 'pq7UvE8LXZlFpl3IU1s6FduE4b6Lt/KXblT/Aqg6vuA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}