SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0e90df0cae4776418625035fa323ff419206746353d4b577a510c7f4a7aa1d49' 
  AND token = 'uutYUi11aGGbZvGNyPiwcgYeqcy35dvJkeVjBTZFiBM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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