SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4e1d092d03d53d6a32671f8688128538f295e576094a924e9604f1176a031898' 
  AND token = 'KaWJTApoD+KuSgjo+IZy/GyRiXTu9hA+LhwN1dQpH/8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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