SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1eaa18a0bf0dd14cb454fb82c519bb997d897487d992ab1e1fa92a9848fd3a2b' 
  AND token = 'WMygqFiln/5fuDTpMjhi7sEylIgsAxMgqvquOBn52ZM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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