SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac615eff57891cb36093ec5b2224e49ff005be24b7fd8e85f7bd846dcc4ecdc8' 
  AND token = '7IZlnq3Mjxr0uIxAYOOGZoAKhdM4eOmtIKg/Ln4d9q8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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