SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb9e8170f699f2d18e02bc87c4adb715a4925fb8b84d6c013a3d3e5d51bba26d' 
  AND token = 'WQvTbW/hK18GuTVUUTGYiIy5wTPDVQ2ojXvUIWG17hE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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