SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7be23e1bcb372f9909f85f40f9ef5b076d047e1501a6723273e1f75143a5e866' 
  AND token = 'miwFt1rzva+IgJ5PMmR5M1x4ggdOOnXtu2NbpmJBLJw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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