SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '34343192b8202e0703411b9eabadee3b414723da93da68bdca9718006adab3ce' 
  AND token = 'Kr5umd/1ctfyYZgNCJghxQnpNCf6fPkRfYuQrjTjRvI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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