SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27a536cb654562e8ca6fb8311576089120a0f48a161684639640b18b0b0af933' 
  AND token = 'inn+KZoQO0y1xXRQCwit+eUurHLTOBbV0XgX4xhlw+A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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