SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f9055fdaf7ed611473adf25d649de82835ccf73feebd4d406b059853be1d05d' 
  AND token = 'qANYEE3gszVoExjAcTM+bfxecj8BzXT3n+vSr/E0uKI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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