SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4604c67707ee88f213708d8e5872aff65a759a02f3077242218a0d504e02435' 
  AND token = 'eWnchoZiPrsNTBPM+KxboJCcgEma0ZsFy3t7JPl+gtA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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