SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20e8807b17aeb2ad3895061415ad0c255a0fa81a6af63a851d138109e6083a2b' 
  AND token = 'etmNBZuJPU/80YesqPFaYBOtU3z02+yI2hxMifF5tS0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00059

JSON explain

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