SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4766c50ea41bd031dce8a0653f7f76098942960b16c41680789e79df3a27bb99' 
  AND token = 'Uu++9qagJQEsduTjuGPNcX7xfU2pyyQ9PRxQSnzcojs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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