SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31c587fb62fbaa5ec5b60aba592995e241499e923c85d7bb56809849e202fc6d' 
  AND token = 'eR9d1Wfmf2tleCeIChZYEETGFQ0UNIrNFhtlPVIYVw0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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