SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fead93185ac2dfa9803f28b63be034d6bff99bbb967b5141958def20c2c1a607' 
  AND token = 'axvHOPxR/PeTMmMxOknxme4QnTsSyMPzN7w/KXx5zcU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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