SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71659a25e5b2c0cd804e743267cbae34d510415285ae4ea2942f789dcfd2e693' 
  AND token = '4UB9j4fbDhASLUXFC/KI35sNJexzhAQkCEhlZ+Shu6w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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