SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'db85ee0ccab7e4a05314b4fa9eeb088d1f6eb30578eb741c43acfcc998458d70' 
  AND token = '6+C774EiKivXSzJZWkvc4Kds1GZMb9xN/lcgE2twBGA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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