SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de783638236c217e82471f2b0c064578833b5bb16512b81949f6d320cb58f00b' 
  AND token = 'emABqr0prlg3UG0TVasBGjTndhxmyPzd3nap5UXF5lE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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