SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aa8fad6f0c48cf8c42069aa0663e51602a23b156d703a535a7b4e2ed6d0b8e57' 
  AND token = 'EUrX4T0KO3wSrVk5cYtbftphCv7VQAnxPoK/mF6TRZQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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