SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2eeefd0e639af30957131adb18da4aa263885899c92ef74f949497e1fd3afb0f' 
  AND token = 'MB7ZthaPB7akH2zloVx9th+IGO2ewOZFynWIn7VtCaE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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