SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bb9abb8ff709ecbaa802fab7bb640c308761d98e4d81f92615fb3ca3ff6090da' 
  AND token = 'f1Y8uFwe+W9DU6UtM+rDydWm4ZhfWlSLb23Jr8fJigM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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