SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '03f75b4775e40d6c35f3b1ad68b3e41b758c5f4402fd40a34451eaaa5265e859' 
  AND token = 'iz35coRzwCSkVoG5SYcSBt2yrzTIJzTudMETW/AhYm4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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