SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b75bdd77be1fc742becebdf618d5283af3d65be1cb77795e1cef0673a0fe6a7' 
  AND token = 'OVSuUstO4Fb8J3+ni67y84uAjbrllRFRO92fI6jLyxA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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