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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3940812b0f3dd1e1ccbfbb525f49fb2754b00246beab6941f30f0e645c7a284c' 
  AND token = 'tHcvSvqGLOavpGFneZdD0dMreLC/Ga69vN3j7LOv9qk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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