SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5d76a724c215588e6540eb4fa2fb72c6fb896e077a75b04dd660c8e8dfa39d6' 
  AND token = 'segfCB0qzou0VeIPqwhj+AMkE3mzDqjUoTiX+hv2W/I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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