SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b068b9a185616a64bf0aaecac23d16e457638ceb1cc78964a87039caf013305' 
  AND token = 'K2g74cMaNSv/TCvTtp4+i5Bpp03cZPUOfXwA8qjKzS0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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