SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2d60ac1da8e5e9701beb792f01654c259231a13808ea678ffcba548ae3a0da3c' 
  AND token = '0ta0YHtplTzNipsivNL0oYpoCFLL/Yb0iCz3czGbdrM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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