SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd90d04cf9d830b458a93464ed920578a26c484f7bcbee07e208f5df3e4cbfb68' 
  AND token = '5BytwiwW2c2geJAZP/iZHtCdBJOWnFpp85VqpzQC/Fo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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