SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a31498029f39b07473b3605e5f25993280c55fbc51c57e906eba890fbc945f6' 
  AND token = '4IX0Jx66POITMyVchhJeuZF8vz+ZEtUAZhtDzSztGd0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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