SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5dbff17ebbb544bcf8e7c4388add5114abf24d8aba0d5a0b5a89741577aeafba' 
  AND token = '6QWbmADn8Q56gTd1KhSOyMyhsxsT6cz0km8/Fi0apSM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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