SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4739ea75c83065ead112e65dfd31cec10573bc1949d9530c0c77b0b1a19fda81' 
  AND token = 'KRzq3yu8dfRdxIN6kt1hfbkJ1xVf7txBW0XNzi6cCek=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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