SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '767ab6834dcb2fb759bf245d629974d231934943592b689b4409f7e140ef0b96' 
  AND token = '7fOirs8Ydtengu1+0AFuN8UR9VEjUeh+3OBb4RrxDWY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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