SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8fe13f2fd85cc5f283a9c69cd76e3e820d69fba616c82c320d0920975febc695' 
  AND token = 'Gz+FKlaLT0XFmHi0cptTj0sZfXeXjZfglPMZHknnzk0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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