SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f888f88b28bb3bd580776139c60d7e79d8f6f8ba48692d9e01956d2aa9ad7142' 
  AND token = 'FYdVc6Bu9ZHhpvG9Jb67KkHc2Y87KWRmHquhk0iBrzU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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