SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2c4a54150aecd8c884701be974bd291d1f37191350a296c6d841354a8bebe46f' 
  AND token = 'KMOmhn6/PXjb0iFXzHthvdqWbCwO1NJeuh8V/1TyPgw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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