SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3828c7955453354aa03aaafd45f2270712af7dac3ee3550ce631fa1cc1aabc83' 
  AND token = 'iaCiarQUReNRWyu26efm8JsLqCkzMVVQIjlfddT7az8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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