SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15d806dbba6ec78aca7b9238fe6ff129e7fc0e01d3a0eb08bcc065920e0643bf' 
  AND token = 'o8Th65OiQaTdPqf9jt/RIAMKGgUcEfKCJboKHqjghok=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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