SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '404f2c20d1e2d879c7410003a12b28a77f024b3ea56815f569bc887099250123' 
  AND token = '/n/l3rZSAqE0yFY+6Oj7EKUyS3KVtz89b8jYSfOibJw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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