SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f19f893d994670f2e2145846ddaceefb6df5919883ac53cc613cea59ee2d8a81' 
  AND token = 'sWMOXtgiVwZIUF8ezSzVWETT6L3WvZs2wt+F7qJLb3Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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