SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a50d4896f135a5ffa635bca20b436ecb1b9afe186ee067ad51bb55973a6efd85' 
  AND token = 'GRmooytlspRGHt1r9pt6qXngvQHiDHX25EoSZcLlwGw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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