SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b779892b77def46defc31b88eaf0e3db94eade76b9312d62fcfbaeddec856f35' 
  AND token = 'U7GQjdoEIZ6NeYQRdL447fq8u1EcnQ94mcGKn3Vj9ns=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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