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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ebc53086106c4a80ad7ec4bfd9d977f2142e4f75da88eaec66c5c457ba78f7c4' 
  AND token = 'HadZ035NROHIy4CiIbhkQAhMPCqZ6Dukq3vRKwTyqOk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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