SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6dc3aa6f06a52365ca937a8b71c68335e086ff1dca45ee105cb4ebd5606fc902' 
  AND token = 'KaZkUQwHWK/UCTHPGJ93SGw6p2P65PvXh7iN4UpqerQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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