SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5abdf28d3d6f3f4cfede8e73459b586a313926b05509c02621d963f1a51fab23' 
  AND token = 'LfJF5D7EYtg03veYYPychMjx8tqtgMRhpBS0JtsMJws=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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