SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2c006dacc7babeb43809e95ada73fc84da963579fad2d17ed911350b77db2719' 
  AND token = '7MJl1HCuwzimWrvjGXPxPSxplpVXSDhGeaT+IuDhhbc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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