SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c761be648bb78989d0f55ca1014009a33d9343a088506542486ffff44177daf' 
  AND token = 'HuXYkqWEbunv/Rs5Vas7TKqIY8a59WsyJ1oIQVXv1Mc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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