SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cf3fa02efb34171f90f85a80d2a283d342320d914144450be14094f3016a45fd' 
  AND token = 'pyJq0UmrriDvznF+F9qu4RQzgvY8yqGHelxwphuG3AQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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