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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd402ba6de7d5c76299401d8711610295dab3087201ca73c077e978e7ea4ef7ec' 
  AND token = '8JWvV06HS5dN0Ba/UnQ0XrMHYY+Eiqy7TfVl1Sn4DKA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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