SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd431b5646b061da85ed7c587397fef6ce162c2d08703dc299fcf501492ca5d55' 
  AND token = 'JNAk73zt6UX0498+IgzwlFsOvwdtxRto0hZ+vxj0AhU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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