SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '19e3e0667bb1eb4b615405c3a4b33cf78eadc275bfb7798826cecd1a7a33be82' 
  AND token = 'LV1QQOIUykRw5lMAyUoTdJfoq3RUqBVjkKp43hggabk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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