SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b29469cb14b45b55fad520d218102b994d121db99c7c4cfeb9926a039c233417' 
  AND token = '8CgjSSY/5kIXPa3UVKrUbf5nn1BoOnRLP3lrYMy9DAs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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