SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0b306df3693eaa047e0799d68effa473ae9139f07e8b62bff732db380a742992' 
  AND token = '2vtvKINZcRjBfJlLW55cA9wgGP5oVhOUG8TCCBRmMpM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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