SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd7d8ca75097db1b126ebc61605fd5b904551644684c1a335d42424792a4cf7e0' 
  AND token = '93yof4xXHYzcsa8Ylm7HZj5B4bTUptsJucGGklsogTc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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