SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5141397f95ef42b464521183552279309ec5d45ff4b488df89359c9eb144786f' 
  AND token = '90l9GCHMKhR0VBAFB+esKHtQACjTeIz4xm6jZ/fLa7Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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