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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a45bdb7218b14a0e975f21a37e46688bf5e69a19e7c2b0978aa8c3dfbd9b52b' 
  AND token = 'JnmuLu2DbHgUCtbZcWn1t502Uev3um/JBlflS7SimHc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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