SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '2134bb6280c96d03785039b4a9653c46b3b7b395a386e255103d529e68de3d7a' 
  AND token = 'S5QgYiu2sGJa5cnO319myoInytkNc604sOoSoiAP4Ak=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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