SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55d22b16cdd8323e91ed9b1058992aa5ff5e2d5b6685a366365fbb22c285d414' 
  AND token = 'ReB1XczZiZPXGFVAXhoEUDOzRSWsk7U4KthEfglmpU8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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