SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '296268c5e842ba916fad9dcc7f55dd7929cc15475c4200f303373645249476db' 
  AND token = 'eIsVAIb5v6UIjaImhOOHfCo929Rssxqh+o1+1eHDNNA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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