SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd933a2c5c907c1478016299b4714441f3121e7e89b9cdc08c759f27debb0e148' 
  AND token = 'QTyAaQWF77JYrdWuXlOEz31OUf7+L41UsKpZwkCi5Es=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}