SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b814010d5ae9043357e8b4d95a4264d0837a5780b08848c79588af2879f852e7' 
  AND token = 'fS0joCi8QAoHqiPv9SEdkCAyab+0l/G9SWk+q1Tfego=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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