SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ea91096e8c03fa27e5954445fdea6e8476a7a7cb99420916b3f88b20cec7282c' 
  AND token = 'lDwPmwIkS+eY4JKbCZjMZos0DboSBNkrY3ZgE8dwXjY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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