SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c29b6236011cbeba772b9ab0787493d475916ad1cc02f8c5a5488863b80e647' 
  AND token = 'YCxLHv3NUr1fWzGBpQTm/vCJY90BHdqYDig+7sQvnB8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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