SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7b0e850fe9c9bbb7049921521b430325b85f24cebd34f479abc933af7ca1d5f1' 
  AND token = '46voQxb6mVbgWaSz12HiycQDgfSDvto8jM1PDzGVCYM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}