SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a90ef9d81a4259c15befce627dc60ee95d53cf2bf2f19074f20e9e4da1354f32' 
  AND token = 'JXsYpGkSa+sJBjTmJKh6rBVdq7r3NR2xf9oQDV4ZOWY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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