SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '08e6da42e1ac14200847510434ab951d9374f951ad5949209e77894cea9efbd0' 
  AND token = 'Vj+OyqVUsIMrtPlayqkDwt6HLkjKrH6BeUB4ALk7tm4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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