SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f12c628c4d6d18434c627006c974c4a3ab200bb12da256e2c0d4244e92cafe4' 
  AND token = 'b3UZjRhIziMDetx23S3tkKqtv3oHha7OB6gGW44iUMA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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