SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20abb204004302e245d4a98712487a12e70430444a89851a2ec054e6fd05a72a' 
  AND token = 'cUXeoKpujC4omFOesxa6Z/uV9kdvzbwYTrUwtJNTiEE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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