SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8f49a4deec54b7d75447c3338eeecfe3e00356b5f0c04d3401571ea9cfb4a63' 
  AND token = 'D2VonP/7gmbFiMANg1AUwOtwSU8q5bGNGfPvm4WE+Lw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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